1. Field of the Invention:
This invention is in the field of retractors used with seat belts.
2. Description of the Prior Art:
Retractors for holding seat belts are generally either automatic locking retractors or emergency locking retractors. One widely used type of seat belt device is the automatic locking retractor wherein once the desired length of seat belt webbing has been pulled or extended from the retractor, a slight retraction or release of tension caused by a slight retracting rotation of the web spool engages an internal locking mechanism preventing further extension of the web. The internal locking mechanism may include a clutch plate rotatably mounted about the spool axis which normally engages and holds a pawl apart frown ratchet teeth formed on the spool. Extension of the predetermined amount of web from the retractor results in rotation of the cam wheel positioning the pawl in a recess formed in the cam wheel thereby allowing the pawl to lockingly engage the spool ratchet teeth preventing further extension. The web must then be retracted into the retractor and rewound on the spool positioning the cam plate apart from the ratchet teeth and allowing for subsequent web extension. The automatic locking retractor thereby locks the web in place once the web has been extended and the web tongue inserted into the buckle mounted to the seat. The disadvantage of an automatic locking retractor is that frequently the retractor will lock if the web is pulled outwardly and then slightly released prior to inserting the web tongue into a buckle. The web must then be retracted and then extended again before the web tongue is locked to the buckle. Automatic locking retractors are also known which replace the rotatable cam wheel by a web follower mounted to the pawl. The web follower contacts the web when fully wound on the spool thereby keeping the pawl located apart from the ratchet teeth until the web is extended thereby decreasing the diameter of the web on the spool and allowing the web follower and pawl to move inwardly until the pawl lockingly engages the spool ratchet teeth.
Emergency locking retractors are known to allow the spool to freewheel even though the web is pulled outwardly to its in use position and the web tongue is locked to the corresponding buckle. An inertial device is operable to normally hold the retractor pawl apart from the spool ratchet teeth and to release the pawl once a predetermined amount of force is applied to the inertial device such as experienced in emergency conditions during rapid de-acceleration or vehicle crash conditions. The advantage of an emergency locking retractor is that the web may be extended over the occupant with the tongue then locked to the corresponding buckle even though the web still may be further extended or retracted as required by the occupant moving relative to the retractor.
Child vehicle seats are available to amount atop the normal passenger seat in a vehicle. Likewise, vehicles are available having an integrated child seat originally built into the passenger seat. In either case, the web or harness must be pulled outwardly from the seat and extended across the child with the web tongue then being lockingly engaged with the corresponding buckle. It is customary to provide a retractor beneath the seat to store the harness web on a spool while allowing the web to be pulled outwardly to an in use position. Neither the prior automatic locking retractors or emergency locking retractors provide the most convenient mechanism for retraction and extension of the web. For example, the automatic locking retractor will automatically lock once a predetermined amount of web has been extended and the web tension slightly released. It can be imagined that it is difficult to place and hold a child in a child seat while at the same time pulling out the web and locking the tongue to the buckle. Frequently, the automatic locking retractor will lock prior to the tongue being lockingly engaged with the buckle necessitating complete retraction of the web and a repeat of the extension cycle. Likewise, the emergency locking retractor, since the spool is not locked, provides the unsatisfactory result that the child may pull the web outwardly and move from the child's seat while the driver is occupied with driving duties. What is needed is a retractor to allow the web to be freely extended and retracted so that the tongue may be inserted into the buckle. Likewise, once the tongue and buckle are locked together, it may be desirable to pull the web outwardly further or retract the web in order to properly position the web relative to the seat and child. At the same time, it is desirable to have such a retractor which will immediately lock upon vehicle movement preventing the child from pulling the web outwardly and moving from the child seat while the vehicle is in motion. In the case of emergency locking retractor, the retractor will lock upon being subjected to a predetermined amount of force such as existing in a rapid de-acceleration but will unlock once the vehicle assumes a level condition without rapid acceleration or de-acceleration. Thus, the child seat retractor should not only lock upon initial vehicle motion but should remain locked even though the vehicle comes to a complete stationary position. The child seat retractor should remain locked until the tongue is unbuckled and the web retracted to its initial position. Last, it is desirable to provide such a retractor which will immediately lock once the web has been extended mad a condition encountered such as a collision with the vehicle prior to initial driving motion. Disclosed herein is such a pre-emergency delayed locking retractor.
It is known to provide automatic locking retractors with some type of time delay. For example. U.S. Pat. Nos. 3,603,525, 3,630,465, 3,858,825 and 3,876,031 disclose delay mechanisms which include an electromagnet or other type of electrical switch for operating the retractor. U.S. Pat. No. 3,648,946 discloses a retractor including a time delay achieved by an impeller within a fluid chamber. Likewise, U.S. Pat. No. 3,632,057 discloses a retractor with a time delay achieved via an air piston. U.S. Pat. Nos. 4,529,144 and 3,635,419 disclose a retractor including a time delay utilizing an inertial mass.